datapath: Consolidate checksum compatibility code.

[sliver-openvswitch.git] / datapath / checksum.h

diff --git a/datapath/checksum.h b/datapath/checksum.h
new file mode 100644 (file)
index 0000000..bf93179
--- /dev/null
+++ b/datapath/checksum.h
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2010 Nicira Networks.
+ * Distributed under the terms of the GNU GPL version 2.
+ *
+ * Significant portions of this file may be copied from parts of the Linux
+ * kernel, by Linus Torvalds and others.
+ */
+
+#ifndef CHECKSUM_H
+#define CHECKSUM_H 1
+
+#include <linux/skbuff.h>
+#include <linux/version.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,22) || \
+       (defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID))
+#define NEED_CSUM_NORMALIZE
+#endif
+
+/* These are the same values as the checksum constants in 2.6.22+. */
+enum csum_type {
+       OVS_CSUM_NONE = 0,
+       OVS_CSUM_UNNECESSARY = 1,
+       OVS_CSUM_COMPLETE = 2,
+       OVS_CSUM_PARTIAL = 3,
+};
+
+#ifdef NEED_CSUM_NORMALIZE
+void compute_ip_summed(struct sk_buff *skb, bool xmit);
+u8 get_ip_summed(struct sk_buff *skb);
+#else
+static inline void compute_ip_summed(struct sk_buff *skb, bool xmit) { }
+static inline u8 get_ip_summed(struct sk_buff *skb)
+{
+       return skb->ip_summed;
+}
+#endif
+
+/* This function closely resembles skb_forward_csum() used by the bridge.  It
+ * is slightly different because we are only concerned with bridging and not
+ * other types of forwarding and can get away with slightly more optimal
+ * behavior.
+ */
+static inline void forward_ip_summed(struct sk_buff *skb)
+{
+#ifdef CHECKSUM_HW
+       if (get_ip_summed(skb) == OVS_CSUM_COMPLETE)
+               skb->ip_summed = CHECKSUM_NONE;
+#endif
+}
+
+#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
+int vswitch_skb_checksum_setup(struct sk_buff *skb);
+#else
+static inline int vswitch_skb_checksum_setup(struct sk_buff *skb)
+{
+       return 0;
+}
+#endif
+
+static inline void set_skb_csum_bits(const struct sk_buff *old_skb,
+                                    struct sk_buff *new_skb)
+{
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,24)
+       /* Before 2.6.24 these fields were not copied when
+        * doing an skb_copy_expand. */
+       new_skb->ip_summed = old_skb->ip_summed;
+       new_skb->csum = old_skb->csum;
+#endif
+#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
+       /* These fields are copied in skb_clone but not in
+        * skb_copy or related functions.  We need to manually
+        * copy them over here. */
+       new_skb->proto_data_valid = old_skb->proto_data_valid;
+       new_skb->proto_csum_blank = old_skb->proto_csum_blank;
+#endif
+}
+
+static inline void get_skb_csum_pointers(const struct sk_buff *skb,
+                                        u16 *csum_start, u16 *csum_offset)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+       *csum_start = skb->csum_start - skb_headroom(skb);
+       *csum_offset = skb->csum_offset;
+#else
+       *csum_start = skb_transport_header(skb) - skb->data;
+       *csum_offset = skb->csum;
+#endif
+}
+
+static inline void set_skb_csum_pointers(struct sk_buff *skb, u16 csum_start,
+                                        u16 csum_offset)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
+       skb->csum_start = csum_start;
+       skb->csum_offset = csum_offset;
+#else
+       skb_set_transport_header(skb, csum_start - skb_headroom(skb));
+       skb->csum = csum_offset;
+#endif
+}
+
+#endif /* checksum.h */